Data transmission methods and apparatuses using the same

ABSTRACT

A mobile communication device with a wireless module and a controller module is provided for improving data throughput by dynamically adjusting a window size of a communication protocol layer. The wireless module performs wireless transceiving to and from a service network. The controller module measures a link quality of the service network associated with a first protocol layer via the wireless module, and determines a number of transmission layers supported for spatial multiplexing associated with the first protocol layer. Also, the controller module adjusts a data transmission parameter associated with a second protocol layer according to the link quality and the number of transmission layers associated with the first protocol layer. Particularly, the second protocol layer is hierarchically higher than the first protocol layer in a multi-layer protocol stack.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application is a Continuation-In-Part (CIP) of U.S. patentapplication Ser. No. 13/290,132, filed on Nov. 7, 2011, which claimspriority of Taiwan Patent Application No. 100127532, filed on Aug. 3,2011. This Application claims priority of U.S. Provisional ApplicationNo. 61/619,839, filed on Apr. 3, 2012, the entirety of which isincorporated by reference herein. Also, this Application claims priorityof U.S. Provisional Application No. 61/642,660, filed on May 4, 2012,the entirety of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention generally relates to data throughput control, and moreparticularly, to apparatuses and methods for improving data throughputby dynamically adjusting a window size of a communication protocollayer.

2. Description of the Related Art

With rapid development in technology, a user may easily connect to anetwork using desktop computers, notebook computers, Personal DigitalAssistants (PDAs) or smart phones. In order for electronic equipmenthaving varying specifications to be able to communicate with the samenetwork, an OSI (Open Systems Interconnection) network model has beenprovided by the ISO (International Organization for Standardization) formanaging the network intercommunication between two systems.

In a network environment in compliance with the OSI model, each layer ofa receiving device or a transmitting device is configured to recognizedata from the same layer. Data packets are sequentially transmitted fromthe top layer to the bottom layer of a transmitting network device andthen transmitted to a receiving network device using applicationprograms. After receiving data packages, the receiving network devicesequentially unpacks each data package, which is then distributed to acorresponding layer thereof. Note that each layer may have varyingtransmission parameters and buffer sizes for their respective processingtasks. However, data stall may occur when data is being transmitted froma faster higher layer to a slower lower layer. Meanwhile, a faster lowerlayer may not improve overall data throughput, if a higher layerencounters an insufficient data buffer or transmission blockages.

BRIEF SUMMARY OF THE INVENTION

Thus, the invention proposes solutions for resolving the aforementionedproblems to improve overall data throughput for a mobile communicationdevice, such as a User Equipment (UE), Mobile Station (MS), MobileTerminal (MT), or others.

In one aspect of the invention, a mobile communication device comprisinga wireless module and a controller module is provided. The wirelessmodule performs wireless transceiving to and from a service network. Thecontroller module measures a link quality of the service networkassociated with a first protocol layer via the wireless module, anddetermines a number of transmission layers supported for spatialmultiplexing associated with the first protocol layer. Also, thecontroller module adjusts a data transmission parameter associated witha second protocol layer according to the link quality and the number oftransmission layers associated with the first protocol layer.Particularly, the second protocol layer is hierarchically higher thanthe first protocol layer in a multi-layer protocol stack.

In another aspect of the invention, a data transmission method for amobile communication device wirelessly connected to a service networkaccording to a multi-layer protocol stack is provided. The methodcomprises the steps of measuring a link quality of the service networkassociated with a first protocol layer, determining a number oftransmission layers supported for spatial multiplexing associated withthe first protocol layer; and adjusting a data transmission parameterassociated with a second protocol layer according to the link qualityand the number of transmission layers associated with the first protocollayer, wherein the second protocol layer is hierarchically higher thanthe first protocol layer in the multi-layer protocol stack.

Other aspects and features of the invention will become apparent tothose with ordinary skill in the art upon review of the followingdescriptions of specific embodiments of the mobile communication devicesand data transmission methods.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 is a block diagram illustrating a network environment accordingto an embodiment of the invention;

FIG. 2 is a block diagram illustrating a multi-layer protocol stack incompliance with the OSI model according to an embodiment of theinvention;

FIG. 3 is an exemplary diagram illustrating the mapping relationsbetween the OSI-model protocol stack and the LTE protocol stackaccording to an embodiment of the invention;

FIG. 4 is a flow chart illustrating the data transmission methodaccording to an embodiment of the invention;

FIG. 5 is a schematic diagram illustrating the processing between thehigher layer and the lower layer in a mobile communication device fordownlink data transmission according to the invention; and

FIG. 6 is a schematic diagram illustrating the processing between thehigher layer and the lower layer in a mobile communication device foruplink data transmission according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best-contemplated mode of carryingout the invention. This description is made for the purpose ofillustrating the general principles of the invention and should not betaken in a limiting sense. The scope of the invention is best determinedby reference to the appended claims.

FIG. 1 is a block diagram illustrating a network environment accordingto an embodiment of the invention. In the network environment 100, themobile communication device 110 is wirelessly connected to the servicenetwork 120 via the air interface for obtaining wireless services. Theservice network 120 comprises at least one cellular access network 121and the core network 122. In general, the cellular access network 121 iscontrolled by the core network 122 to provide the functionality ofwireless transceiving, and the cellular access network 121 may compriseone or more cellular stations, such as base stations, Node-Bs, orevolved Node-B (eNB), depending on the radio access technology in use.Although not shown, the core network 122 may further enable interfacingwith external networks, such as the Public Switched Telephone Network(PSTN), which is called the Circuit Switched (CS) domain functionality,and/or interfacing with the Internet Protocol (IP) based Network, suchas the Internet, which is called the Packet Switched (PS) domainfunctionality.

The mobile communication device 110 comprises a wireless module 111 anda controller module 112, wherein the wireless module 111 is configuredto perform the functionality of wireless transceiving and the controllermodule 112 is configured to control the operation of the wireless module111. To further clarify, the wireless module 111 may be a RadioFrequency (RF) unit (not shown), and the controller module 112 may be ageneral-purpose processor or Micro-Control Unit (MCU) of a baseband unit(not shown). The baseband unit may contain multiple hardware devices toperform baseband signal processing, including analog to digitalconversion (ADC)/digital to analog conversion (DAC), gain adjusting,modulation/demodulation, encoding/decoding, and so on. The RF unit mayreceive RF wireless signals, convert the received RF wireless signals tobaseband signals, which are processed by the baseband unit, or receivebaseband signals from the baseband unit and convert the receivedbaseband signals to RF wireless signals, which are later transmitted.The RF unit may also contain multiple hardware devices to perform radiofrequency conversion. For example, the RF unit may comprise a mixer tomultiply the baseband signals with a carrier oscillated in the radiofrequency of the wireless communications system, wherein the radiofrequency may be 900 MHz, 2100 MHz, or 2.6 GHz utilized in Long TermEvolution (LTE) or LTE-Advanced technology, or others depending on theradio access technology in use. Although not shown, the mobilecommunication device 110 may further comprise other functionalcomponents, such as a display unit and/or keypad serving as theMan-Machine Interface (MMI), a storage unit storing the program codes ofapplications, or others.

FIG. 2 is a block diagram illustrating a multi-layer protocol stack incompliance with the OSI model according to an embodiment of theinvention. From bottom to top, Layer 1˜Layer 7 sequentially include aphysical layer, data link layer, network layer, transport layer, sessionlayer, presentation layer, and application layer. The physical layer isdefined as the bottom layer closest to the hardware devices, while theapplication layer is defined as the top layer closest to the softwareprograms. In general, Layers 1 through 3 deal with network access andLayers 4 through 7 deal with end-to-end communications between themessage source and the message destination. Each layer includes at leastone function that is contained between an upper and a lower logicalboundary. The services of each layer are combined with the services ofthe lower layers to create new services that are made available to thehigher layers.

Specifically, the physical layer and the data link layer in the OSImodel are configured to handle network hardware connection and may beimplemented on various network access interfaces, such as Ethernet,Token-Ring or Fiber Distributed Data Interface (FDDI), etc. The networklayer in the OSI model is configured to deliver messages between atransmitting device and a receiving device using various protocols, suchas identifying addresses or selecting transmission paths using InternetProtocol (IP), Address Resolution Protocol (ARP), Reverse AddressResolution Protocol (RARP), or Internet Control Message Protocol (ICMP).The transport layer in the OSI model is configured to deliver messagesbetween different hosts using Transmission Control Protocol (TCP) andUser Datagram Protocol (UDP). The session layer, the presentation layer,and the application layer in the OSI model are configured to providevarious application protocols, such as TELNET, FTP, SMTP, POP3, SNMP,NNTP, DNS, NIS, NFS, and HTTP. The present invention may be applied toany wireless network system having a multi-layer structure of protocollayers for data transmission.

Note that, in the OSI model, various wireless communication standards,such as WiFi, GSM/GPRS, WCDMA, CDMA2000, LTE, and LTE-Advanced, etc.,may be employed to enable signaling and communication between atransmitter and a receiver through the network layer. FIG. 3 is anexemplary diagram illustrating the mapping relations between theOSI-model protocol stack and the LTE protocol stack according to anembodiment of the invention. As shown in FIG. 3, the physical layer inthe OSI model is replaced with the LTE Layer 1 which provides radioaccess using the Frequency-Division Duplexing/Time-Division Duplexing(FDD/TDD) or Orthogonal Frequency Division Multiplexing/Single-CarrierFrequency-Division Multiple Access (OFDMA/SC-FDMA) technology. The datalink layer in the OSI model is replaced with the LTE Layer 2 whichcomprises the sub-layers Medium Access Control (MAC), Radio Link Control(RLC), and Packet Data Convergence Protocol (PDCP). The network layer inthe OSI model is partially replaced with the LTE sub-layers RadioResource Control (RRC) and Non-Access Stratum (NAS). In addition to theLTE sub-layers RRC and NAS, the network layer also comprises an entitywhich adopts IP for handling addressing, routing, service typespecification, packet fragmentation, packet reassembling and security.The transport layer in the OSI model adopts TCP for handling packetsequence numbers, acknowledgement packets, checksums andre-transmissions. The session layer, the presentation layer, and theapplication layer in the OSI model are configured to provide applicationprotocols.

FIG. 4 is a flow chart illustrating the data transmission methodaccording to an embodiment of the invention. The data transmissionmethod may be applied in a mobile communication device, such as themobile communication device 110, for dynamically adjusting a window sizeof a communication protocol layer to improve data throughput. To begin,the mobile communication device measures a link quality of a servicenetwork associated with a first protocol layer (step 410). Next, themobile communication device determines a number of transmission layerssupported for spatial multiplexing associated with the first protocollayer (step S420). After that, the mobile communication device adjusts adata transmission parameter associated with a second protocol layeraccording to the link quality and the number of transmission layersassociated with the first protocol layer (step S430). Specifically, thesecond protocol layer is hierarchically higher than the first protocollayer in a multi-layer protocol stack. Note that, the data transmissionparameter may be applied for downlink data transmission, or uplink datatransmission, or both downlink and uplink data transmissions.

For the embodiment of FIG. 3, the link quality in step S410 may be aChannel Quality Indicator (CQI) of a downward transmission link from theservice network, and the number of transmission layers in step S420 maybe a Rank Indicator (RI) used in Multiple-Input Multiple-Output (MIMO),while the first protocol layer may be the physical layer in the LTEprotocol stack. The data transmission parameter in step S430 may be aTCP/IP window size, while the second protocol layer may be the networklayer or the transport layer in the OSI-model protocol stack which hasthe lower three layers replaced with the LTE protocol stack. Forexample, in step S420, if a 2×2 MIMO is employed, the RI equals to 2, orelse, if MIMO is not employed, the RI equals to 1. Specifically, in stepS430, the data transmission parameter may be adjusted by applying thefollowing formula:

$\left( {{MaxTCPWindowSize} - {MinTCPWindowSize}} \right) \times {\frac{{CQI\_ Indexed}{\_ TBS}}{{MAX\_ CQI}{\_ TBS}} \div R}\; I \times {Weight}$wherein MaxTCPWindowSize represents the maximum TCP/IP window size,MinTCPWindowSize represents the minimum TCP/IP window size,CQI_Indexed_TBS represents a Transport Block Size (TBS) corresponding tothe measured CQI, MAX_CQI_TBS represents another TBS corresponding tothe maximum CQI, and Weight represents a constant or a weightingfunction of the TBS corresponding to the measured CQI.

Specifically, the maximum CQI may be determined according to the Table7.2.3-1 specified in the 3GPP TS 36.213 specification, and the TBScorresponding to the measured CQI and the TBS corresponding to themaximum CQI may be determined by looking up the Tables 7.1.7.1-1 and7.1.7.2.1-1 specified in the 3GPP TS 36.213 specification, wherein theTables 7.1.7.1-1 and 7.1.7.2.1-1 describe the mapping relations betweenthe Modulation and Coding Scheme (MCS) index and TBS index. If Weight isa weighting function of the measured CQI, the weighting function may bea linear function, a non-linear function, or a discrete function, aslong as the weighting function keeps the measured CQI and the TCP/IPwindow size in positive correlation.

It is to be understood that, the CQI and the TCP/IP window size aremerely illustrative embodiments, and other parameters associated withlink quality and data transmission rates may be used instead, and theinvention is not limited thereto. Likewise, the LTE protocol stack ismerely an illustrative embodiment, and other wireless communicationsprotocol may be used instead to replace the lower layers in the OSImodel.

To clearly illustrate the advantages of the invention, the followingdescription is given using the TCP/IP window size as an example of thedata transmission parameter in step S430. As known in the art, theconcept of a sliding window is used in TCP/IP for allowing multiplepackets to be transmitted before a receiving device acceptsacknowledgement packets. This kind ofmulti-transmission-multi-acknowledgement technology can increase networkbandwidth utilization and the data transmission speed. Simply speaking,a receiving device may inform a transmitting device of the availablebuffer size for receiving packets using the TCP/IP window size. Thetransmitting device may decrease its data throughput when the TCP/IPwindow size drops, or increase its data throughput when the TCP/IPwindow size rises. Therefore, the invention may improve data throughputby dynamically adjusting the TCP/IP window size in the higher protocollayer, e.g., the network/transport layer, according to the link qualityand number of transmission layers supported for spatial multiplexingobtained by the lower protocol layer, e.g., the physical layer.

FIG. 5 is a schematic diagram illustrating the processing between thehigher layer and the lower layer in a mobile communication device fordownlink data transmission according to the invention. As shown at theleft side of FIG. 5, a scenario is depicted where a bad link quality,i.e., small CQI value, is measured and/or the number of transmissionlayers supported for spatial multiplexing is small, i.e., small RIvalue, in the lower layer, indicating that the lower layer can onlyprovide low-speed wireless transmissions. Conventionally, the higherlayer does not take the link quality and the number of transmissionlayers supported for spatial multiplexing obtained by the lower layerinto account for determining the TCP/IP window size, and waste of powerconsumption and data stall may occur if the higher layer determines touse a large TCP/IP window size for high speed data transmission.Advantageously, for this scenario, the invention allows the higher layerto dynamically reduce the TCP/IP window size, so that power consumptionmay be saved and overall data throughput may be improved.

As shown at the right side of FIG. 5, another scenario is depicted wherea good/fair link quality, i.e., large CQI value, is measured and/or thenumber of transmission layers supported for spatial multiplexing islarge, i.e., large RI value, in the lower layer, indicating that thelower layer can provide high-speed wireless transmissions.Conventionally, the higher layer may determine to use a small TCP/IPwindow size for low speed data transmission while the lower layer mayprovide high-speed wireless transmissions. Advantageously, for thisscenario, the invention allows the higher layer to dynamically increasethe TCP/IP window size, so that overall data throughput may be improved.

Similarly, FIG. 6 is a schematic diagram illustrating the processingbetween the higher layer and the lower layer in a mobile communicationdevice for uplink data transmission according to the invention. As shownat the left side of FIG. 6, a scenario is depicted where a bad linkquality, i.e., small CQI value, is measured and/or the number oftransmission layers supported for spatial multiplexing is small, i.e.,small RI value, in the lower layer, and correspondingly, the higherlayer dynamically reduces the TCP/IP window size. As shown at the rightside of FIG. 6, another scenario is depicted where a good/fair linkquality, i.e., large CQI value, is measured and/or the number oftransmission layers supported for spatial multiplexing is large, i.e.,large RI value, in the lower layer, indicating that the lower layer canprovide high-speed wireless transmissions, and correspondingly, thehigher layer dynamically increases the TCP/IP window size. Thus, theoverall data throughput for downlink data transmission may be improved.

While the invention has been described by way of example and in terms ofpreferred embodiment, it is to be understood that the invention is notlimited thereto. Those who are skilled in this technology can still makevarious alterations and modifications without departing from the scopeand spirit of this invention. Therefore, the scope of the inventionshall be defined and protected by the following claims and theirequivalents.

What is claimed is:
 1. A mobile communication device, comprising: awireless module, performing wireless transceiving to and from a servicenetwork; and a processor, measuring a Channel Quality Indicator (CQI) ofa downward transmission link from the service network associated with alayer via the wireless module, determining a Rank Indicator (RI) usedfor Multiple-Input Multiple-Output (MIMO) associated with the Physicallayer, and adjusting a Transmission Control Protocol (TCP) or InternetProtocol (IP) window size associated with a Transport layer or Networklayer according to the CQI of the downward transmission link and the RIused for MIMO associated with the Physical layer, wherein the Transportlayer or Network layer is hierarchically higher than the Physical layerin a multi-layer protocol stack, and wherein the adjusted TCP or IPwindow size equals to:$\left( {{MaxTCPWindowSize} - {MinTCPWindowSize}} \right) \times {\frac{{CQI\_ Indexed}{\_ TBS}}{{MAX\_ CQI}{\_ TBS}} \div R}\; I \times {Weight}$wherein the MaxTCPWindowSize represents a maximum TCP/IP window size,the MinTCPWindowSize represents a minimum TCP/IP window size, theCQI_Indexed_TBS represents a Transport Block Size (TBS) corresponding tothe measured CQI, the MAX_CQI_TBS represents another TBS correspondingto a maximum CQI, and the Weight represents a constant or a weightingfunction of the measured CQI.
 2. The mobile communication device ofclaim 1, wherein the TCP or IP window size is applied for downlink datatransmission, or uplink data transmission, or both downlink and uplinkdata transmissions.
 3. The mobile communication device of claim 1,wherein the wireless transceiving to and from the service network isperformed using the Long Term Evolution (LTE) technology.
 4. A datatransmission method for a mobile communication device wirelesslyconnected to a service network according to a multi-layer protocolstack, comprising: measuring a Channel Quality Indicator (CQI) of adownward transmission link from the service network associated with aPhysical layer; determining a Rank Indicator (RI) used forMultiple-Input Multiple-Output (MIMO) associated with the Physicallayer; and adjusting a Transmission Control Protocol (TCP) or InternetProtocol (IP) window size associated with a Transport layer or Networklayer according to the CQI of the downward transmission link and the RIused for MIMO associated with the Physical layer, wherein the Transportlayer or Network layer is hierarchically higher than the Physical layerin the multi-layer protocol stack, and wherein the adjusted TCP or IPwindow size equals to:$\left( {{MaxTCPWindowSize} - {MinTCPWindowSize}} \right) \times {\frac{{CQI\_ Indexed}{\_ TBS}}{{MAX\_ CQI}{\_ TBS}} \div R}\; I \times {Weight}$wherein the MaxTCPWindowSize represents a maximum TCP/IP window size,the MinTCPWindowSize represents a minimum TCP/IP window size, theCQI_Indexed_TBS represents a Transport Block Size (TBS) corresponding tothe measured CQI, the MAX_CQI_TBS represents another TBS correspondingto a maximum CQI, and the Weight represents a constant or a weightingfunction of the measured CQI.
 5. The data transmission method of claim4, wherein the TCP or IP window size is applied for downlink datatransmission, or uplink data transmission, or both downlink and uplinkdata transmissions.
 6. The data transmission method of claim 4, whereincommunications between the mobile communication device and the servicenetwork are performed using the Long Term Evolution (LTE) technology.